| 摘要 |
PURPOSE:To obtain a multi-layer pipe whose layer detaining property is excellent, by placing a wire body on one or more layers, and making the layers adhere tightly to each other by using a die or/and a core bar. CONSTITUTION:In case of manufacturing a multi-layer pipe by a sinking cold drawing method, an inner layer pipe 2 to which a wire body 1 is wound is inserted into an outer layer pipe 3 whose one end is mouth-worked in advance. Subsequently, the pipe 3 and the pipe 2 are brought to diameter reduction by a die 4 part successively from the mouth part side of the pipe 3 passing through the inside of the die 4, by a drawing machine which is not shown in the figure, and formed to a multi-layer pipe. In this case, when the die 4 passes through the inside surface of the pipe 3, it contacts by pressing to the outside surface of the pipe 2, therefore, the wire body 1 is pushed into both the pipe 2 and the pipe 3. Accordingly, in the part where the wire body 1 is pushed in, the pipe 2 and the pipe 3 become as if they were detained by a screw mechanism, and a strong detaining operation is exerted on a shearing force operating on the layer boundary of the pipe 2 and the pipe 3. According to this method, a multi- layer steel pipe and a thick multi-layer steel pipe having a composite performance whose layer detaining property is good are obtained easily. |
